Hot air furnace



A. C. WATSON HOT AIR FURNACE Nov. 8, 1932.

Filed Sept. 6, 1950 Patented Nov. 8, 1932 PATENT OFFICE ANDREW COATES WATSON, OF TORONTO, ONTARIO, CANADA nor AIR FURNACE Application filed September The principal objects of the invention are, to obtain the maximum transference of heat from the fuel consumed and to devise a sheet metal furnace structure which will not permit '35 the escape of gases of combustion into the air heating chambers. v

A further and important object is to devise a construction which may be manufactured at moderate cost and is of light weight jg and may be easily handled.

The principal features of the invention consist in the novel construction of the combustion chamber of a welded sheet metal structure having a central air heating chamlg' ber surrounded by an annular chamber having flue extensions leading to a common main flue leading centrally therefrom, and in the novel construction and arrangement of air chambers surrounding said combustion chamher, whereby the air is directed into heating contact with substantially the entire surface of the combustion chamber and flues.

In the accompanying drawing, Figure 1 is a perspective View in part vertical section,

of a furnace constructed in accordance with this invention.

Figure 2 is a vertical sectional View through the furnace taken on the line 2-2 of Figure 3.

Figure 3 is a plan section of the furnace taken on the line 33 of Figure 2.

In the heating of air for the purposes of heating dwellings it is very important that the leakage of gases of combustion into the air heating chambers be avoided. Many types of construction in common use depend upon the joints in the combustion chamber being rendered gas tight by the use of cement. Such constructions moreover are extremely limited in the actual heating areas exposed to the circulation of air to be heated.

In the present invention the combustion chamber is formed of sheet metal and all joints are securely welded and are gas tight.

In the construction herein shown a cylinder 1 of sheet metal has a Vertical welded joint 2 and extends upwardly from the base plate 3 being held in a centered position by a flange 4. A flanged ring 5 secured to the inner wall 6, 1930. Serial No. 480,223.

of the cylinder 1 forms a support for the grate 6 and the cylindrical fire pot 7 which may be of any suitable material.

Rectangular openings 8 and 9 are formed in the cylinder below and above the fire pot and form the ash pit and fire door openings respectively. Flanges 10 and 11 extend outwardly from the cylinder around the said openings.

A cylinder 12 of smaller diameter than the interior of the cylinder 1 is arranged within the upper end of the cylinder 1 and forms an annular fluespace 13.

The bottom of the cylinder 12 is closed by a plate 14 welded to the bottom edge which is preferably protected from undue expansion by a suitable shield 15.

A plurality of flues 16, preferably rectangular in cross section extend inwardly from the top of the flue space 13 and the top of the flue space 13 between the flues 16 is sealed with closures 17 which preferably slope upwardly and outwardly. The flues 16 open into a common flue 18 which leads to the smoke pipe and all the joints of said flue structure are butted and welded in gas tight joints.

A plurality of cylindrical thimbles 19 are arranged between the cylinders 1 and 12 immediately above the bottom plate 14 and form air passages to the chamber enclosed by the cylinder 12. The edges of these thimbles are also Welded securely in place with gas tight joints. Arched hoods 20 are secured to the outer wall of the cylinder 1 at the outer ends of the thimbles to deflect a flow of air inwardly through the thimbles.

A flange ring 21 is secured to the cylinder 1 at its upper end and extends horizontally outward therefrom and openings 22 are formed therein in radial alignment with the flues 16. I I

An outer casing 23 of cylindrical form is mounted in the base plate 3 and is held in place spaced from the cylinder 1 by the flanges 24, said casing engaging the flanged perimeter 24 of the'flange ring 21 and extending thereabove.

A flanged circular plate 25 closes the top v,

of the cylindrical casing 23 and is spaced above the flues 16 forming a chamber 26 above the ring 21.

Openings 27 are formed in the casing 23 at the bottom thereof to admit a flow of air to be heated which may be directed thereto by suitable pipes and vertical baflles 28 are arranged to extend outwardly from the cylinder 1 to divide the air flowinginwajrdly. I

A vertical baflle 29 is arranged between the feed door flange 11 and the flange ring 21 and a vertical baflie 30 is arranged diametrically opposite thereto and extends from the base plate to the flange ring 21. a I

The vertical baifles 29 and 30prevent a swirling flow of air around the cylinderl and the air flowing inwardly through the openings 27, after being first directed laterally into contact with the entiresurface of the cylinder 1 is directed upwardly.

Part of the air flowing upwardly in the heating chamberA between the outer casing 23 and the heat transferring cylinder 1 is deflected by the arched hoods 20 to flow through the thimbles 19 to the inner heating chamber B. It will be noted that the thimbles 19 and their hoods 20 are arranged vertically below the openings 22 in the flange ring 21, consequently the direct flow of air to the openings 22 is checked, the remaining volume of air rising the chamber Astriking this flange ring 21 and is then deflected thereby tofind egress through the openings 22.

Openings 31 are arranged at the upper ends of. the vertical baflles29 and 30.

The air entering the central chamber B is heated by contact with the inner surfaces of Cylinder 12Iand flows upwardly through the spaces between the flues 16 and is further heated by contact withthe flues.

I They top plate 25 is formed with a plurality of pipe openings 26 which are arranged in radial alignment with the passages between the flues 16 and the bevelled surfaces 17 diiser the air upwardly and outwardly thereto. The air rising through the openings in the flange plate 21 isdirected over the upper surfaces of the flues 16. a a v It will be understood from this description that the flow of air is directed into heat exchanging contact with practically the en.- tire heated surface of the metal enclosing the combustion chamber and fluesjand as the structure is all sheet metal a rapid transfer is effected and the maximum heating efiiciency-is obtained.

The welding of all joints makes the struc ture gas tight and yet permits the maximum movement of the metal in expansion and contraction without rupture.

The entire structure with the the grates and fire pot lining can be produced by dies with great accuracy and at the minimum cost and the erection and completion of the structurecan be accomplished with ease and celerity. &

exception of What I claim as my invention is 1. In a hot air furnace, asheet metal cylin 7 cent said flues, acommon flue connecting said spaced flues, and closure member secured in the upper end of said cylindrical casing pa ed em Said part tion n f rm g therewith and with said cylinder and cylin: drical casing an airereceiving chamber enclosingsaid flues.

a h t ai furn h et m ta y inder, a cylindrical casing spaced from and n s n i yli er an ext nding there? above, afirepot within said cylinder, an air chamber arranged within the upper end of said cylinder, spaced flues leading upwardly and inwardly at theupper end of the flue space surrounding said air chamber, a 601.11: mon flue connecting said spaced flues, air ducts leading from the space between the outer casing and said cylinderto the inner air chamber, means for directing a flow of air through said air ducts, a flange ring arranged e w n he t p, of a y nder: an the u r casing having openings therethrough in radial alignment with said flues, and a top closing said outer casing spaced above said flange ri n a d? spaced: flu a hav n air ducts offsetin relation to the openings in the flange ring. a

I bet air fu nace a c m s n. chamher and a plurality of converging flues formed of sheet metal members welded per manently together in gas tight joints, an outer casing spaced from said combustion chamber and torming an annular air heating chamber therearound, an inner heating chamber connected; with the aforesaid heating chamber by openings, said openings having arched hoods sloping downwardly into said annular air-heating chamber to induce upwardly flowing air therefrom into said an,-

nular heating chamber, and battles disposed heating chamber arranged inthe upper part of said cylinder, an outer casing enclosing saidsheet metal cylinder and forming there: with an outer air heating chamber, hooded passages directing air from said outer air chamber to theother. air chamber, anda plurality of fines leading from the interior of said sheet metal cylinder and converging radially toward said central flue and connected therewith and presenting an extended heat exchange area, said outer casing having partitions forming an end enclosure for said flues, said respective chambers having outlet openings directing air therefrom into intimate heat exchange contact with said flues.

5. In a hot air furnace, a sheet metal cylinder, a sheet metal cylinder arranged within the upper end of the aforesaid cylinder and spaced therefrom, spaced flues leading from the space between said cylinders, a partition arranged below said flues, said cylinders having air ducts extending therethrough, an outer cylinder encircling said first-mentioned cylinder and forming therewith an air heating chamber surrounding the first mentioned cylinder, said partition closing the upper end of said latter air heating chamber and having openings in alignment with said flues for directing air in close proximity thereto, and sloping hoods positioned above said air ducts and extending, into the last-mentioned air heating chamber for directing a flow of air through the ducts into the second-mentioned cylinder.

6. In a hot air furnace, a sheet metal cylinder, a cylindrical casing spaced from and enclosing said cylinder and extending thereabove, a firepot within said cylinder, said cylinder having a central air chamber above said firepot, flues leading from the inner cylinder, air ducts leading from the top of said casing, cold air ducts leading through the bottom of said casing, vertical baffles presenting divergent areas adapted to direct the inflow of air to said casing laterally to either side of said openings, vertical battles between said cylinder and casing and disposed between the respective baiHes to limit the lateral flow of air, and bafiies arranged below said top air ducts to divert a portion of the direct upward flow of air from alignment with said top air ducts and into said central air chamher.

7. A furnace composed of outer, inner and intermediate sheet metal cylindrical sections, the intermediate section comprising a tubular integral section extending from bottom to top of the outer section forming; an air space therebetween, said inner section comprising a drum connected at its lower end with said air space, a common chamber receiving heated air from said air space and from said inner section, a flanged ring secured directly to the sheetmetal wall of said intermediate member in spaced relation to the bottom, a grate supported on said ring, an insulating lining supported by said ring and lining the sheet metal wall of said intermediate section torming a combustion chamber and protecting the sheet metal wall of said intermediate section from the heat of combustion, and an insulating lining on the bottom of said intermediate section protecting the sheet metal wall thereof from the direct heat of combustion.

ANDREW GOATES WATSON. 

